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WO1996028191A1 - Process for producing polymer microparticles, microparticles produced using said process, and the use of such particles in medical diagnostics - Google Patents

Process for producing polymer microparticles, microparticles produced using said process, and the use of such particles in medical diagnostics Download PDF

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Publication number
WO1996028191A1
WO1996028191A1 PCT/EP1996/001107 EP9601107W WO9628191A1 WO 1996028191 A1 WO1996028191 A1 WO 1996028191A1 EP 9601107 W EP9601107 W EP 9601107W WO 9628191 A1 WO9628191 A1 WO 9628191A1
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WO
WIPO (PCT)
Prior art keywords
microparticles
poly
solvent
ultrasound
lactide
Prior art date
Application number
PCT/EP1996/001107
Other languages
German (de)
French (fr)
Inventor
Georg Rössling
Celàl ALBAYRAK
Matthias Rothe
Original Assignee
Schering Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Schering Aktiengesellschaft filed Critical Schering Aktiengesellschaft
Priority to AT96908039T priority Critical patent/ATE241388T1/en
Priority to US08/913,312 priority patent/US6468506B1/en
Priority to DE59610478T priority patent/DE59610478D1/en
Priority to EP96908039A priority patent/EP0822836B1/en
Priority to JP52728696A priority patent/JP3943130B2/en
Priority to CA002214778A priority patent/CA2214778C/en
Publication of WO1996028191A1 publication Critical patent/WO1996028191A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/22—Echographic preparations; Ultrasound imaging preparations ; Optoacoustic imaging preparations
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/22—Echographic preparations; Ultrasound imaging preparations ; Optoacoustic imaging preparations
    • A61K49/222—Echographic preparations; Ultrasound imaging preparations ; Optoacoustic imaging preparations characterised by a special physical form, e.g. emulsions, liposomes
    • A61K49/223—Microbubbles, hollow microspheres, free gas bubbles, gas microspheres
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P43/00—Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones

Definitions

  • the invention relates to the subject characterized in the claims, that is, a process for the production of gas-containing microparticles for ultrasound diagnostics, the wall material of which is composed of polyesters of ⁇ -, ⁇ - or ⁇ -hydroxycarboxylic acids, particles which can be prepared by this process, and their Use in medical diagnostics.
  • Ultrasonic waves are reflected at interfaces from different types of tissue.
  • the resulting echo signals are electronically amplified and made visible.
  • EP 0 131 540 describes the stabilization of the gas bubbles by sugar. Although this improves the reproducibility and homogeneity of the contrast effect, these bubbles do not survive passage through the lungs.
  • EP 0 122 624 and 0 123 235 describe that the gas bubble stabilizing effect of sugars, sugar alcohols and salts is improved by adding surface-active substances.
  • These ultrasound contrast agents provide a capillary passability and the possibility of displaying the arterial thigh and various organs such as the liver or spleen.
  • the contrast effect is limited to the vessel lumen, since the vesicles are not absorbed by the tissue cells.
  • Encapsulation of gases such as air as an ultrasound contrast medium, is described in EP 0 224 934.
  • the wall material used here consists of protein, in particular human serum albumin with the known allergenic properties, to which cytoxic effects can be added by denaturation.
  • Patent specification EP 0 327 490 describes gas-containing microparticles for ultrasound diagnostics based on biodegradable, synthetic materials.
  • ⁇ -, ⁇ - or ⁇ -hydroxycarboxylic acids are also disclosed as biodegradable polymers. Although these agents have a sufficient in vivo lifespan and are enriched intracellularly in the reticuloendothelial system and thus also in the liver or spleen after intravenous administration, the particles based on hydroxycarboxylic acids prepared according to the examples of this application show only a relatively low backscattering coefficient. The diagnostic effectiveness of the contrast medium preparations prepared from it is therefore not satisfactory in all cases.
  • the object of the present invention was therefore to provide an improved process for the preparation of microparticles based on polyesters of ⁇ -, ⁇ - or ⁇ -hydroxycarboxylic acids, according to which it is possible to obtain particles which have a better backscatter coefficient than the particles of the prior art Technology.
  • the particles and the contrast agent preparations prepared from them should continue to meet the other requirements placed on a modern contrast agent, such as be sufficiently small and stable to reach the left half of the heart after intravenous administration without significant loss of gas and essentially quantitatively, be well tolerated without possessing an allergenic potential and not clump in the aqueous medium.
  • microparticles based on polyesters of ⁇ -, ⁇ - or ⁇ -hydroxycarboxylic acids can be produced by the respective polyester and optionally a surface-active substance in an organic solvent or solvent mixture, of which at least one solvent is readily miscible with water is dissolved, then a liquid perfluoro compound or water is dispersed in this solution and then this dispersion is dispersed in water containing a surface-active substance by means of a stirrer, the solvent being removed by introducing gas and applying a vacuum.
  • particles precipitate that initially still contain water or the liquid perfluoro compound. Then the particle containing
  • the suspension is mixed with a suitable pharmaceutically acceptable cyroprotector and freeze-dried, the liquid in the particles largely escaping and being replaced by the desired gas (usually air) after the lyophilizer has been aerated. Depending on the drying time, a small amount of the liquid (water or perfluoro compound) may remain in the particles as vapor.
  • Perfluoropentane, perfluorohexane, perfluoro-1, 3-dimethylcyclohexane, perfluorocyclohexene, perfluorodecalin or perfluoroether are preferably used as the perfluoro compound.
  • polymers Polyglycolide (PGA) and its copolymers with L-lactide (PGA / PLLA) or polylactide (PLA) as well as its stereocopolymers such as poly-L-lactide (PLLA), poly-DL-lactide or poly-L-lactide / DL-lactide or poly-ß-hydroxybutyrate (PHBA) and its copolymers with ß-hydroxy valerate (PHBA / HVA) or poly-ß-hydroxypropionate (PHPA) or poly-p-dioxanone (PDS) or poly- ⁇ -valerolactone or poly- ⁇ -caprolactone.
  • PGA Polyglycolide
  • PGA / PLLA polylactide
  • PLA polylactide
  • stereocopolymers such as poly-L-lactide (PLLA), poly-DL-lactide or poly-L-lactide / DL-lactide or poly-ß-hydroxybutyrate (PHBA) and
  • the molar ratio is in the range from 85:15 to 50:50, preferably 75:25.
  • organic solvent or solvent mixtures for the polymers are preferably used, dichloromethane, acetone, ethyl acetate, methyl acetate, triacetin, triethyl acetate, ethyl lactate, isopropyl acetate, propyl formate, butyl formate, ethyl formate and / or methyl lactate.
  • Substances from the group of Poloxamere ® or Poloxamine ® polyethylene glycol alkyl ethers, polysorbates, sucrose esters (Sistema The Netherlands), sucrose esters [Ryoto sugar ester, (Tokyo)], gelatin, polyvinyl pyrolidone, fatty alcohol polyglycoside, chaps ( Serva), Chap (Calbiochem), Chapso (Calbiochem), decyl- ⁇ -D-glycopyranoside, decyl- ⁇ -D-maltopyranoside, dodecyl- ⁇ -D-maltopyranoside, sodium oleate, polyethylene glycol, polyvinyl alcohol or mixtures thereof.
  • Air, nitrogen and oxygen are used as gases.
  • An alternative method for producing microparticles based on polyesters of ⁇ -, ⁇ - or ⁇ -hydroxycarboxylic acids is that the desired polymer (s) and optionally an amino acid is dissolved in at least one organic solvent ( ), this solution is sprayed through a nozzle into a column which is filled with or through which a supercritical gas flows, the solvent being taken up by the supercritical gas.
  • the same substances are used as polymers or copolymers as were mentioned in the first-mentioned production process.
  • An amino acid is preferably added to the dissolved polymer (polyester) used in each case instead of the surfactant.
  • L-lysine, L-phenylalanine, L-tryptophan and D, L-phenylalanine are preferably used as amino acids.
  • the solvents listed in the first process variant are suitable as solvents or solvent mixtures.
  • the supercritical gases used are nitrous oxide, carbon dioxide, halogenated hydrocarbons, saturated or unsaturated hydrocarbons, nitrogen dioxide and / or ammonia, carbon dioxide being preferred.
  • the supercritical gases can optionally contain up to 10% additives such as e.g. lower alcohols such as Ethanol, esters or gases such as Contain nitrogen
  • the size of the resulting particles can be controlled via the type, size and shape of the injection nozzle, working pressure and temperature in the column.
  • a particle size as required for an intravenously applied ultrasound contrast medium ( ⁇ 10 ⁇ m) can be used using a nozzle with a nozzle diameter of 0.5 mm and a spray angle of 10 ° at a working pressure between 90 and 100 bar, preferably 94-96 bar and a temperature of 36 ° C can be realized.
  • Another aspect of the invention relates to microparticles for ultrasound diagnostics which can be produced by the aforementioned methods.
  • Another aspect of the invention relates to contrast agents for ultrasound diagnostics containing microparticles that were produced by the aforementioned methods.
  • These agents can be obtained by resuspending the dried microparticles in a pharmaceutically acceptable suspension medium.
  • Possible pharmaceutically acceptable suspension media are, for example, water pi, aqueous solutions of one or more inorganic salts such as physiological electrolyte solutions and buffer solutions, such as Tyrode, aqueous solutions of mono- or disaccharides such as glucose or lactose, sugar alcohols such as mannitol, which may also contain an additional one surfactant, e.g. from the group of polysorbates or polysaccharides, polyvinylpyrrolidone, polyethylene glycol, sucrose mono- and diesters or substances from the group of poloxamers or poloxamines or their mixtures and / or a physiologically compatible polyhydric alcohol such as glycerol.
  • water suitable for injection purposes is water suitable for injection purposes.
  • the suspension can be filtered immediately before injection.
  • microparticles produced by the processes according to the invention based on polyesters of ⁇ -, ⁇ - or ⁇ -hydroxycarboxylic acids or contrast agents prepared therefrom meet all the requirements placed on an ultrasound contrast agent.
  • the particles contained in the agents are characterized by the following advantages:
  • Degradation products are toxicologically harmless, they circulate in the bloodstream for a sufficiently long time, they can be used in all modes of ultrasound diagnostics, especially also in modes in which nonlinear effects are used, they are well tolerated, they show a uniform, controllable size distribution, they are easy to manufacture, the polymeric particles have a narrow molecular weight distribution, • they are sufficiently stable to survive passage through the lungs and are therefore also suitable for contrasting the left heart and • they are absorbed by the reticuloendothelial system and are therefore also suitable for contrasting the liver and Spleen.
  • the particles produced by the process according to the invention show a larger backscattering coefficient in comparison to the particles disclosed in EP 0 327 490, which are likewise composed of ⁇ -, ⁇ -, ⁇ -hydroxycarboxylic acids. This could be shown in a comparative experiment. So for a freshly prepared suspension of the particles described in EP 0 327 490 (Example 1) in water (concentration 18.6 mg / ml) after 5 minutes
  • the backscatter coefficients are determined in an in vitro test setup in which the backscattered signal caused by a contrast medium in a cuvette is measured (see also "Standardization of the measurement of acoustical parameters of ultrasound contrast agents” First European Symposium on Ultrasound Contrast Imaging, January 25-26, 1996, Rotterdam).
  • the emulsion (0/0 / W) is transferred to a 2 1 three-necked flask equipped with a stirrer (300 rpm), the solvent is removed at 20 ° C. for 3 hours by ⁇ introduction, and at 25 ° C. for 3 hours .
  • the suspension is then mixed with a cryoprotector and freeze-dried.
  • the particle diameter was determined using an LS-130 from Coulter Electronics GmbH, which uses a combination of light scattering and Eisenhofer diffraction. The number of particles was determined using a Coulter Counter.
  • Example 2 The procedure is as in Example 1, with perfluoropentane being replaced by perfluorodecalin.
  • the lyophilisate resuspended with the water contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 2 The procedure is as in Example 1, with perfluoropentane being replaced by perfluorohexane.
  • the lyophilisate resuspended with 0.9% NaCl solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • the lyophilisate resuspended with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 2 The procedure is as in Example 1, with perfluoropentane being replaced by perfluoroheptane.
  • the lyophilisate resuspended with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 10 procedure is as in Example 1 using perfluoropentane is replaced by perfluorohexane and the polymer Resomer ® RG-502 by Resomer ® RG-858 and dissolved in 65 ml of methylene chloride / acetone (volume 63:37). That with water Lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 13 The procedure is as in Example 1, with acetone being replaced by ethyl acetate.
  • the water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • the procedure is as in Example 1, the acetone being replaced by methyl acetate.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 16 Procedure is as in Example 1, wherein the polymer Resomer ® RG-502 is replaced by Resomer ® RG-858 and acetone by ethyl acetate.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 - 8 ⁇ m.
  • Example 2 The procedure is as in Example 1, the perfluoropentane being replaced by 10 ml of 20% glucose solution.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 2 The procedure is as in Example 1, using only 2 g of Polymer Resomer ® RG-502 instead of 3 g.
  • the lyophilisate taken up with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.1 to 8 ⁇ m.
  • Example 2 Is as in Example 1, wherein the polymer Resomer ® RG-502 by LG PHB / PHN copolymer (12% PHV, Biopol ICI), gelatin solution through 200 ml, 1%
  • the water-resuspended lyophilisate contains ultrasound-active microparticles of
  • Example 2 The procedure is as in Example 1, with the polymer Resomer ® RG 502 using 1 g PHB / PVB copolymer (18% PHV, Biopol ICI), gelatin solution using 200 ml 1% PVA solution in 30 ml methylene chloride / acetone (volume fraction 66: 34) is solved.
  • the lyophilisate resuspended with the water contains ultrasound-active microparticles with a diameter of 0.4 to 8 ⁇ m.
  • Example 21 Procedure is as in Example 1, wherein the polymer Resomer ® RG 502 by 1 g Polycaprolactome [inherent vis: 1.26 dl / g in CHC1 3 at 30 ° C (Birmingham Polymers NC, USA], gelatin by 200 ml 1% PVA solution (MW 9-10 kDal), the polymer is dissolved in 30 ml methylene chloride / acetone (70:30 by volume) The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 ⁇ m.
  • Example 21 Example 21
  • Example 2 The procedure is as in Example 1, with gelatin being replaced by 400 ml of 0.5% Na oleate solution.
  • the lyophilisate absorbed with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.5 to 8 ⁇ m.
  • Example 23 The procedure is as in Example 1, with gelatin being replaced by 400 ml, 1% octyl- ⁇ -D-glucopyranoside solution.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 8 ⁇ m.
  • Example 2 The procedure is as in Example 1, with the gelatin solution being mixed with 400 ml, 1% sucrose pitate P-1570 (Ryoto Sugarester).
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 ⁇ m.
  • Example 2 The procedure is as in Example 1, with gelatin solution being mixed with 400 ml, 1% sucrose stearate (Ryoto Sugarester) S-1670.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 ⁇ m.
  • Example 2 The procedure is as in Example 1, with 400 ml, 1% sucrose diester, SP 70 (Sisternen, The Netherlands) being used instead of gelatin solution.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 ⁇ m.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 5 ⁇ m.
  • the procedure is as in Example 1, with acetone being replaced by ethyl acetate.
  • the water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 ⁇ m.
  • Example 2 The procedure is as in Example 1, with acetone being replaced by methyl acetate.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 7 ⁇ m.
  • Example 2 The procedure is as in Example 1, with acetone being replaced by methyl lactate.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 6 ⁇ m.
  • EXAMPLE 31 The procedure is as in Example 1, acetone being replaced by ethyl acetate.
  • the water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 6 ⁇ m.
  • the procedure is as in Example 1, with acetone being replaced by triacetin.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 7 ⁇ m.
  • Example 2 The procedure is as in Example 1, with acetone being replaced by triethyl citrate.
  • the water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 7 ⁇ m.
  • Example 34 0.375 g of L-lysine (Aldrich) are dissolved in 25 ml of glacial acetic acid (Merck); 2.5 g Resomer ® RG-756 (Böhringer Ingelheim) are dissolved in 75 ml dichloromethane (Merck). The combined solutions were further treated in an apparatus as shown in FIG. 1.
  • the combined solutions are first placed in a reservoir (17) and the system is filled with the gas from a supply bottle via valve (2) and line (30).
  • the solution is removed from the reservoir (17) by means of a piston stroke pump (16) after flowing through line (52), a heat exchanger (15), a line (54). a valve (20) and finally line (55) to the nozzle (118).
  • the copolymer-containing solution is sprayed into the column (12) through a conventional single-substance nozzle (118) [Schlick 121 V], while at the same time CO2 in the supercritical state at 90 bar / 36 ° C and a throughput of 8.9 kg / h in cocurrent, is passed through the column via inlet (8).
  • the nozzle has a diameter of 0.5 mm, the spray angle is 10 °.
  • the further steps essentially serve to clean and recycle the solvent-laden CO 2 , but have nothing to do with the production of the particles.
  • the CO 2 can be processed as follows.
  • the gas loaded with the solvent flows through lines (42) and (40), controlled by 2 solenoid valves (7 and 9), to the end of the column and is expanded to 60 bar.
  • the Valves are switched so that the amount of fluid gas flowing into the column per unit of time can escape while maintaining the working pressure of the column.
  • the CO 2 which has been cooled to 60 bar by the expansion and is loaded with solvent, is fed via line (62) into the separator (10), which is heated to 21 ° C., where the solvent mixture separates out in the CO as a result of the greatly reduced solubilities under these conditions.
  • the CO 2 freed from the solvent mixture is transferred again to the supercritical state by means of line (64 and 32) by increasing the pressure and temperature (3 and 4) (90 bar, 36 ° C.) and again to the column via line to further dry the resulting particles (34), LPG pump (4), line (36), heat exchanger (5), line (38) through inlet (8).
  • the solvent mixture separated in the separator (10) is removed after separating the separator (10) from the circuit by means of valves (6) and (13) and relaxing to atmospheric pressure via the valve (72).
  • Ultrasound-active, gas-containing microparticles with a diameter of 5-10 ⁇ m are obtained.
  • Example 34 Further microparticles are produced analogously to Example 34.
  • the polymers used in each case and further data are summarized in Table 1.
  • the ultrasound-active, hollow microparticles obtained are sterile and free from solvent residues, polymerization catalysts or initiator molecules. They have a uniform particle size distribution of 5 to 10 ⁇ m.
  • the polymers are each dissolved in 75 ml dichloromethane (Merck) and 25 ml glacial acetic acid, the respective amount of amino acid is added.
  • D, L-phenylalanine is suitably pre-dissolved in up to 50 ml of ethanol (Merck).

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Abstract

The invention concerns a process for producing gas-containing microparticles for use in ultrasound diagnostics and with wall material formed from polyesters of α-, β-, or η-hydroxycarboxylic acids. The invention also concerns particles produced using the process in question and the use of such particles in medical diagnostics.

Description

Verfahren zur Herstellung von polymeren Mikropartikeln, nach diesen Verfahren hergestellte Mikropartikel sowie deren Verwendung in der medizinischen Diagnostik Process for the production of polymeric microparticles, microparticles produced by these processes and their use in medical diagnostics

Die Erfindung betrifft den in den Patentansprüchen gekennzeichneten Gegenstand, daß heißt ein Verfahren zur Herstellung von gasenthaltenden Mikropartikeln für die Ultraschalldiagnostik, deren Wandmaterial aus Polyestem von α-, ß- oder γ- Hydroxycarbonsäuren aufgebaut ist, Partikel die nach diesem Verfahren herstellbar sind, sowie deren Verwendung in der medizinischen Diagnostik.The invention relates to the subject characterized in the claims, that is, a process for the production of gas-containing microparticles for ultrasound diagnostics, the wall material of which is composed of polyesters of α-, β- or γ-hydroxycarboxylic acids, particles which can be prepared by this process, and their Use in medical diagnostics.

Die Ultraschalldiagnostik hat in der Medizin wegen der komplikationslosen einfachen Handhabung sehr breite Anwendung gefunden. Ultraschallwellen werden an Grenzflächen von unterschiedlichen Gewebearten reflektiert. Die dabei entstehenden Echosignale werden elektronisch verstärkt und sichtbar gemacht.Ultrasound diagnostics have found widespread use in medicine because of the simple, uncomplicated handling. Ultrasonic waves are reflected at interfaces from different types of tissue. The resulting echo signals are electronically amplified and made visible.

Die Darstellung von Blutgefäßen und innerer Organen mittels Ultraschall erlaubt im allgemeinen nicht die Darstellung des darin vorhandenen Blutflusses. Flüssigkeiten, insbesondere Blut, liefern nur dann Ultraschallkontrast, wenn Dichte- und Kompresibilitätsunterschiede zur Umgebung bestehen. Als Kontrastmittel werden in der medizinischen Ultraschalldiagnostik z. B. Gase enthaltende oder Gas produzierende Substanzen verwendet, da der Impedanzunterschied zwischen Gas und umgebendem Blut wesentlich größer ist, als der von Flüssigkeiten oder Festkörpern und Blut [Levine R.A., J. Am. Coll. Cardiol. 3 (1989) 28 ; Machi I.J. CU 11 (1983) 3].The visualization of blood vessels and internal organs using ultrasound generally does not allow the visualization of the blood flow contained therein. Liquids, especially blood, only provide ultrasound contrast if there are differences in density and compressibility to the environment. As a contrast medium in medical ultrasound diagnostics such. B. Gas-containing or gas-producing substances are used, since the impedance difference between gas and surrounding blood is much larger than that of liquids or solids and blood [Levine R.A., J. Am. Coll. Cardiol. 3 (1989) 28; Machi I.J. CU 11 (1983) 3].

Roelandt et al. [Ultrasound Med. Biol. 8 (1982) 471-492] beschreiben, daß durch periphere Injektionen von Lösungen, die feine Gasblasen enthalten, cardiale Echokontraste erzielt werden können. Diese Gasblasen werden in physiologisch verträglichen Lösungen z.B. durch Schütteln, andere Agitation oder durch Zusatz von Kohlendioxid erhalten. Sie sind jedoch hinsichtlich Anzahl und Größe nicht standardisiert und können nur unzulänglich reproduziert werden. Auch sind sie in der Regel nicht stabilisiert, so daß ihre Lebensdauer gering ist. Ihre mittleren Durchmesser liegen meist über Erythrocytengröße, so daß keine Lungenkapillarpassage mit nachfolgender Kontrastierung von Organen wie linkes Herz, Leber, Niere oder Milz möglich ist. Darüber hinaus eignen sie sich nicht für Quantifizierung, da sich das von ihnen erzeugte Ultraschallecho aus mehreren, nicht voneinander zu trennenden Prozessen wie Blasenentstehung, Koaleszenz und Auflösung zusammensetzt. So ist es z.B. nicht möglich, mit Hilfe dieser Ultraschall- Kontrastmittel über die Messung des Kontrastverlaufs im Myokard, Aussagen über die Transitzeiten zu gewinnen. Hierzu sind Kontrastmittel notwendig, deren Streukörper eine ausreichende Stabilität aufweisen.Roelandt et al. [Ultrasound Med. Biol. 8 (1982) 471-492] describe that cardiac echo contrasts can be achieved by peripheral injections of solutions containing fine gas bubbles. These gas bubbles are obtained in physiologically compatible solutions, for example by shaking, other agitation or by adding carbon dioxide. However, they are not standardized in number and size and can only be reproduced inadequately. They are also usually not stabilized, so that their lifespan is short. Their mean diameters are usually above erythrocyte size, so that no lung capillary passage with subsequent contrasting of organs such as the left heart, liver, kidney or spleen is possible. In addition, they are not suitable for quantification, since the ultrasound echo they generate is composed of several processes that cannot be separated, such as bubble formation, coalescence and dissolution. For example, it is not possible to use these ultrasound Contrast agent by measuring the contrast curve in the myocardium to gain information about the transit times. Contrast agents are necessary for this purpose, the scattering bodies of which have sufficient stability.

In der EP 0 131 540 ist die Stabilisierung der Gasblasen durch Zucker beschrieben. Damit wird zwar die Reproduzierbarkeit und Homogenität des Kontrasteffektes verbessert, eine Lungenpassage überstehen diese Blasen jedoch nicht.EP 0 131 540 describes the stabilization of the gas bubbles by sugar. Although this improves the reproducibility and homogeneity of the contrast effect, these bubbles do not survive passage through the lungs.

In den EP 0 122 624 und 0 123 235 wird beschrieben, daß der gasblasenstabilisierende Effekt von Zuckern, Zuckeralkoholen und Salzen durch Zusatz von grenzflächenaktiven Substanzen verbessert wird. Eine Lungenkapillargängigkeit und die Möglichkeit zur Darstellung des arteriellen Gefäßschenkels und verschiedener Organe wie Leber oder Milz ist bei diesen Ultraschallkontrastmitteln gegeben. Der Kontrasteffekt ist hierbei jedoch auf das Gefaßlumen beschränkt, da die Bläschen nicht von den Gewebezellen aufgenommen werden.EP 0 122 624 and 0 123 235 describe that the gas bubble stabilizing effect of sugars, sugar alcohols and salts is improved by adding surface-active substances. These ultrasound contrast agents provide a capillary passability and the possibility of displaying the arterial thigh and various organs such as the liver or spleen. However, the contrast effect is limited to the vessel lumen, since the vesicles are not absorbed by the tissue cells.

Keines der beschriebenen Ultraschall-Kontrastmittel verbleibt längere Zeit unverändert im Körper. Eine Organdarstellung mit ausreichender Signalintensität durch selektive Anreicherung nach i.v. Gabe oder Quantifizierung sind mit diesen Mitteln nicht möglich.None of the ultrasound contrast agents described remain unchanged in the body for a long time. An organ display with sufficient signal intensity through selective enrichment after i.v. These funds cannot be used for administration or quantification.

Eine Verkapselung von Gasen, wie beispielsweise Luft als Ultraschall-Kontrastmittel wird in der EP 0 224 934 beschrieben. Das hierbei verwendete Wandmaterial besteht aus Protein, insbesondere menschliches Serumalbumin mit den bekannten allergenen Eigenschaften, zu denen durch eine Denatuierung cytoxische Effekte hinzukommen können.Encapsulation of gases, such as air as an ultrasound contrast medium, is described in EP 0 224 934. The wall material used here consists of protein, in particular human serum albumin with the known allergenic properties, to which cytoxic effects can be added by denaturation.

In der Patentschrift EP 0 327 490 werden gasenthaltende Mikropartikel für die Ultraschall-Diagnostik auf der Basis von biologisch abbaubaren, synthetischen Materialien beschrieben. Als bioabbaubare Polymere werden u.a. auch α-, ß- oder γ- Hydroxycarbonsäuren offenbart. Diese Mittel weisen zwar eine ausreichende in vivo Lebensdauer auf und werden nach intravenöser Applikation intrazellulär im retikuloendothelialem System und damit auch in der Leber oder Milz angereichert, jedoch zeigen die gemäß den Beispielen dieser Anmeldung hergestellten Partikel auf Basis von Hydroxycarbonsäuren nur einen relativ geringen Rückstreukoeffizenten. Die diagnostische Wirksamkeit daraus bereiteter Kontrastmittelpräparationen ist daher nicht in allen Fällen befriedigend. Aufgabe der vorliegenden Erfindung war es daher ein verbessertes Verfahren zur Herstellung von Mikropartikeln auf der Basis von Polyestem von α-, ß- oder γ- Hydroxycarbonsäuren bereitszustellen, nach welchem es gelingt Partikel zu erhalten, die einen besseren Rückstreukoeffizienten aufweisen als die Partikel des Standes der Technik.Patent specification EP 0 327 490 describes gas-containing microparticles for ultrasound diagnostics based on biodegradable, synthetic materials. Α-, β- or γ-hydroxycarboxylic acids are also disclosed as biodegradable polymers. Although these agents have a sufficient in vivo lifespan and are enriched intracellularly in the reticuloendothelial system and thus also in the liver or spleen after intravenous administration, the particles based on hydroxycarboxylic acids prepared according to the examples of this application show only a relatively low backscattering coefficient. The diagnostic effectiveness of the contrast medium preparations prepared from it is therefore not satisfactory in all cases. The object of the present invention was therefore to provide an improved process for the preparation of microparticles based on polyesters of α-, β- or γ-hydroxycarboxylic acids, according to which it is possible to obtain particles which have a better backscatter coefficient than the particles of the prior art Technology.

Die Partikel und daraus bereitete Kontrastmittelpräparationen sollten weiterhin die übrigen an ein modernes Kontrastmittel gestellten Anforderungen erfüllen, wie z.B. ausreichend klein und stabil sein, um ohne nennenswerten Gasverlust und im wesentlichen quantitativ die linke Herzhälfte nach intravenöser Applikation zu erreichen, eine gute Verträglichkeit aufweisen ohne ein allergenes Potential zu besitzen und nicht im wäßrigen Medium verklumpen.The particles and the contrast agent preparations prepared from them should continue to meet the other requirements placed on a modern contrast agent, such as be sufficiently small and stable to reach the left half of the heart after intravenous administration without significant loss of gas and essentially quantitatively, be well tolerated without possessing an allergenic potential and not clump in the aqueous medium.

Diese Aufgabe wird durch die vorliegende Erfindung gelöst.This object is achieved by the present invention.

Es wurde gefunden, daß Mikropartikeln auf der Basis von Polyestem von α-, ß- oder γ-Hydroxycarbonsäuren hergestellt werden können, indem der jeweilige Polyester und gegebenenfalls eine oberflächenaktive Substanz in einem organischen Lösungsmitteln oder Lösungsmittelgemischen, von denen mindestens ein Lösungsmittel mit Wasser gut mischbar ist, gelöst wird, anschließend eine flüssige Perfluoro- Verbindung oder Wasser in dieser Lösung dispergiert wird und anschließend diese Dispersion in Wasser, das eine oberflächenaktive Substanz enthält, mittels eines Rührers dispergiert wird, wobei das Lösungsmittel durch Gaseinleitung und Anlegen eines Vakuums entfernt wird. Hierbei fallen Partikel aus, die zunächst noch Wasser bzw. die flüssige Perfluoro- Verbindung enthalten. Anschließend wird die Partikel enthaltendeIt has been found that microparticles based on polyesters of α-, β- or γ-hydroxycarboxylic acids can be produced by the respective polyester and optionally a surface-active substance in an organic solvent or solvent mixture, of which at least one solvent is readily miscible with water is dissolved, then a liquid perfluoro compound or water is dispersed in this solution and then this dispersion is dispersed in water containing a surface-active substance by means of a stirrer, the solvent being removed by introducing gas and applying a vacuum. Here, particles precipitate that initially still contain water or the liquid perfluoro compound. Then the particle containing

Suspension mit einem geeigneten pharmazeutisch akzeptablen Kyroprotektor vermischt und gefriergetrocknet, wobei die in den Partikeln befindliche Flüssigkeit weitgehend entweicht und nach Belüften des Lyophilisators durch das gewünschte Gas (in der Regel Luft) ersetzt wird. Je nach Trocknungsdauer verbleibt gegebenenfalls eine geringe Menge der Flüssigkeit (Wasser bzw. Perfluoro- Verbindung) als Dampf in den Partikeln.The suspension is mixed with a suitable pharmaceutically acceptable cyroprotector and freeze-dried, the liquid in the particles largely escaping and being replaced by the desired gas (usually air) after the lyophilizer has been aerated. Depending on the drying time, a small amount of the liquid (water or perfluoro compound) may remain in the particles as vapor.

Als Perfluoro- Verbindung kommen vorzugsweise zur Anwendung Perfluoropentan, Perfluorohexan, Perfluoro-1 ,3-Dimethylcyclohexan, Perfluorocyclohexen, Perfluorodecalin oder Perfluoroether.Perfluoropentane, perfluorohexane, perfluoro-1, 3-dimethylcyclohexane, perfluorocyclohexene, perfluorodecalin or perfluoroether are preferably used as the perfluoro compound.

Als Polymere werden in dem erfindungsgemäßen Verfahren eingesetzt: Polyglycolid (PGA) sowie dessen Copolymere mit L-Lactid (PGA/PLLA) oder Polylactid (PLA) sowie dessen Stereocopolymere wie z.B. Poly-L-Lactid (PLLA), Poly-DL-Lactid oder Poly-L-Lactid/DL-Lactid oder Poly-ß-hydroxybutyrat (PHBA) sowie dessen Copolymere mit ß-Hydroxy valerat (PHBA/HVA) oder Poly-ß-hydroxypropionat (PHPA) oder Poly-p-dioxanon (PDS) oder Poly-δ- valerolacton oder Poly-ε-caprolacton.The following polymers are used as polymers: Polyglycolide (PGA) and its copolymers with L-lactide (PGA / PLLA) or polylactide (PLA) as well as its stereocopolymers such as poly-L-lactide (PLLA), poly-DL-lactide or poly-L-lactide / DL-lactide or poly-ß-hydroxybutyrate (PHBA) and its copolymers with ß-hydroxy valerate (PHBA / HVA) or poly-ß-hydroxypropionate (PHPA) or poly-p-dioxanone (PDS) or poly-δ-valerolactone or poly-ε -caprolactone.

Bei den Copolymeren zwischen Milchsäure (LA) und Glycolsäure (GA) liegt das Molverhältnis bezogen auf die Monomeren im Bereich von 85: 15 bis 50:50, vorzugsweise bei 75:25.In the copolymers between lactic acid (LA) and glycolic acid (GA), the molar ratio, based on the monomers, is in the range from 85:15 to 50:50, preferably 75:25.

Als organische Lösungs- oder Lösungsmittelgemische für die Polymeren werden bevorzugt verwendet, Dichlormethan, Aceton, Ethylacetat, Methylacetat, Triacetin, Triethy leitrat, Ethyllactat, Isopropylacetat, Propylformiat, Butylformiat, Ethylformiat und/oder Methyllactat.As organic solvent or solvent mixtures for the polymers are preferably used, dichloromethane, acetone, ethyl acetate, methyl acetate, triacetin, triethyl acetate, ethyl lactate, isopropyl acetate, propyl formate, butyl formate, ethyl formate and / or methyl lactate.

Als oberflächenaktive Substanz (Tensid) kommen zur Anwendung Substanzen aus der Gruppe der Poloxamere® oder Poloxamine®, Polyethylenglycol Alkylether, Polysorbate, Saccharoseester (Sistema The Netherlands), Saccharoseester [Ryoto sugarester, (Tokyo)], Gelatine, Polyvinylpyrolidon, Fettalkoholpolyglycosid, Chaps (Serva), Chap (Calbiochem), Chapso (Calbiochem), Decyl-ß-D-glycopyranosid, Decyl-ß-D-maltopyranosid, Dodecyl-ß-D-maltopyranosid, Natriumoleat, Polyethylenglykol, Polyvinylalkohol oder deren Gemische.Substances from the group of Poloxamere ® or Poloxamine ® , polyethylene glycol alkyl ethers, polysorbates, sucrose esters (Sistema The Netherlands), sucrose esters [Ryoto sugar ester, (Tokyo)], gelatin, polyvinyl pyrolidone, fatty alcohol polyglycoside, chaps ( Serva), Chap (Calbiochem), Chapso (Calbiochem), decyl-β-D-glycopyranoside, decyl-β-D-maltopyranoside, dodecyl-β-D-maltopyranoside, sodium oleate, polyethylene glycol, polyvinyl alcohol or mixtures thereof.

Als Gase kommen zur Anwendung Luft, Stickstoff, Sauerstoff. Edelgase, Distickstoffoxid, Kohlendioxid, Halogenkohlenwasserstoffe, gesättigte oder ungesättigte gasförmige Kohlenwasserstoffe, Stickstoffdioxid und/oder Ammoniak.Air, nitrogen and oxygen are used as gases. Noble gases, nitrous oxide, carbon dioxide, halogenated hydrocarbons, saturated or unsaturated gaseous hydrocarbons, nitrogen dioxide and / or ammonia.

Ein alternatives Verfahren zur Herstellung von Mikropartikeln auf der Basis von Polyestem von α-, ß- oder γ-Hydroxycarbonsäuren, besteht darin, daß (die) gewünschte(n) Polymer(e) und gegebenenfalls eine Aminosäure in mindestens einem organischen Lösungsmittel gelöst wird (werden), diese Lösung über eine Düse in eine Kolonne gesprüht wird, die mit einem überkritischen Gas befüllt ist oder von diesem durchströmt wird, wobei das Lösungsmittel vom überkritischen Gas aufgenommen wird.An alternative method for producing microparticles based on polyesters of α-, β- or γ-hydroxycarboxylic acids is that the desired polymer (s) and optionally an amino acid is dissolved in at least one organic solvent ( ), this solution is sprayed through a nozzle into a column which is filled with or through which a supercritical gas flows, the solvent being taken up by the supercritical gas.

Als Polymere bzw. Copolymere kommen in dieser Verfahrensvariante dieselben Substanzen zur Anwendung, wie sie im erstgenannten Herstellungsverfahren genannt wurden. Entsprechendes gilt für die Mischungsverhältnisse bei den Copolymeren. Vorzugsweise wird zu dem jeweils verwendeten gelösten Polymer (Polyester) anstelle des Tensids eine Aminosäure gegeben. Als Aminosäuren kommen vorzugsweise zum Einsatz L-Lysin, L-Phenylalanin, L-Tryptophan sowie D,L-Phenylalanin.In this process variant, the same substances are used as polymers or copolymers as were mentioned in the first-mentioned production process. The same applies to the mixing ratios of the copolymers. An amino acid is preferably added to the dissolved polymer (polyester) used in each case instead of the surfactant. L-lysine, L-phenylalanine, L-tryptophan and D, L-phenylalanine are preferably used as amino acids.

Als Lösungsmittel bzw. Lösungsmittelgemische eignen sich die in der ersten Verfahrensvariante aufgeführten Lösungsmittel.The solvents listed in the first process variant are suitable as solvents or solvent mixtures.

Die Zugabe einer Perfluorverbindung ist in diesem Falle nicht erforderlich.The addition of a perfluoro compound is not necessary in this case.

Als überkritische Gase werden verwendet, Distickstoffoxid, Kohlendioxid, Halogenkohlenwasserstoffe, gesättigte oder ungesättigte Kohlenwasserstoffe, Stickstoffdioxid und/oder Ammoniak, wobei Kohlendioxid bevorzugt ist. Die überkritischen Gase können gegebenenfalls bis zu 10% Zusätze wie z.B. niedere Alkohole wie z.B. Ethanol, Ester oder Gase wie z.B. Stickstoff enthaltenThe supercritical gases used are nitrous oxide, carbon dioxide, halogenated hydrocarbons, saturated or unsaturated hydrocarbons, nitrogen dioxide and / or ammonia, carbon dioxide being preferred. The supercritical gases can optionally contain up to 10% additives such as e.g. lower alcohols such as Ethanol, esters or gases such as Contain nitrogen

Die Größe der resultierenden Partikel kann über Art, Größe und Form der Einspritzdüse, Arbeitsdruck und Temperatur in der Kolonne gesteuert werden. Eine Partikelgröße wie sie für ein intravenös appliziertes Ultraschallkontrastmittel erforderlich ist ( < 10 μm) kann unter Verwendung einer Düse mit einem Düsendurchmesser von 0,5 mm und einem Sprühwinkel von 10° bei einem Arbeitsdruck zwischen 90 und 100 bar, vorzugsweise 94-96 bar und einer Temperatur von 36° C realisiert werden.The size of the resulting particles can be controlled via the type, size and shape of the injection nozzle, working pressure and temperature in the column. A particle size as required for an intravenously applied ultrasound contrast medium (<10 μm) can be used using a nozzle with a nozzle diameter of 0.5 mm and a spray angle of 10 ° at a working pressure between 90 and 100 bar, preferably 94-96 bar and a temperature of 36 ° C can be realized.

Ein weiterer Aspekt der Erfindung betrifft Mikropartikel für die Ultraschalldiagnostik herstellbar nach den vorgenannten Verfahren.Another aspect of the invention relates to microparticles for ultrasound diagnostics which can be produced by the aforementioned methods.

Ein weiterer Aspekt der Erfindung betrifft Kontrastmittel für die Ultraschalldiagnostik enthaltend Mikropartikel die nach den genannte Verfahren hergestellt wurden.Another aspect of the invention relates to contrast agents for ultrasound diagnostics containing microparticles that were produced by the aforementioned methods.

Diese Mittel können erhalten werden, indem die getrockneten Mikropartikel in einem pharmazeutisch akzeptablen Suspensionsmedium resuspendiert werden.These agents can be obtained by resuspending the dried microparticles in a pharmaceutically acceptable suspension medium.

Als pharmazeutisch akzeptable Suspensionsmedien kommen beispielsweise infrage Wasser p.i., wäßrige Lösungen eines oder mehrere anorganische Salze wie physiologische Elektrolyt-Lösungen und Pufferlösungen, wie z.B. Tyrode, wäßrige Lösungen von Mono- oder Disacchariden wie Glucose oder Lactose, Zuckeralkoholen wie Mannit, die gegebenenfalls zusätzlich noch eine oberflächenaktive Substanz, z.B. aus der Gruppe der Polysorbate oder Polysaccharide, Polyvinylpyrrolidon, Polyethylenglykol, Saccharose Mono- und Diester oder Substanzen aus der Gruppe der Poloxamere oder Poloxamine oder deren Gemische und/oder einem physiologisch verträglichen mehrwertigen Alkohol wie Glycerin. Bevorzugt ist jedoch in für Injektionszwecke geeignetes Wasser.Possible pharmaceutically acceptable suspension media are, for example, water pi, aqueous solutions of one or more inorganic salts such as physiological electrolyte solutions and buffer solutions, such as Tyrode, aqueous solutions of mono- or disaccharides such as glucose or lactose, sugar alcohols such as mannitol, which may also contain an additional one surfactant, e.g. from the group of polysorbates or polysaccharides, polyvinylpyrrolidone, polyethylene glycol, sucrose mono- and diesters or substances from the group of poloxamers or poloxamines or their mixtures and / or a physiologically compatible polyhydric alcohol such as glycerol. However, preferred is water suitable for injection purposes.

Um die Sicherheit der Applikation zu erhöhen, kann unmittelbar vor Injektion eine Filtration der Suspension durchgeführt werden.To increase the safety of the application, the suspension can be filtered immediately before injection.

Die nach den erfindungsgemäßen Verfahren hergestellten Mikropartikel auf der Basis von Polyestem von α-, ß- oder γ-Hydroxycarbonsäuren bzw. daraus bereitete Kontrastmittel erfüllen alle Anforderungen die an ein Ultraschallkontrastmittel gestellt werden. Die in den Mitteln enthaltenen Partikel zeichnen sich durch die folgenden Vorteile aus:The microparticles produced by the processes according to the invention based on polyesters of α-, β- or γ-hydroxycarboxylic acids or contrast agents prepared therefrom meet all the requirements placed on an ultrasound contrast agent. The particles contained in the agents are characterized by the following advantages:

Sie werden schnell in-vivo abgebaut,They are quickly broken down in vivo,

Abbauprodukte sind toxikologisch unbedenklich, sie zirkulieren ausreichend lange im Blutkreislauf, sie sind in allen Modi der Ultraschalldiagnostik, insbesondere auch bei Modi bei denen nichtlineare Effekte ausgenutzt werden anwendbar, sie sind gut verträglich, sie zeigen eine einheitliche, steuerbare Größenverteilung, sie sind leicht herstellbar, die polymeren Partikel weisen eine enge Molekulargewichtsverteilung auf, • sie sind ausreichend stabil um auch eine Lungenpassage zu überstehen und eignen sich damit auch für die Kontrastierung des linken Herzens und • sie werden vom retikuloendothelialen System aufgenommen und eignen sich damit auch für die Kontrastierung der Leber und Milz.Degradation products are toxicologically harmless, they circulate in the bloodstream for a sufficiently long time, they can be used in all modes of ultrasound diagnostics, especially also in modes in which nonlinear effects are used, they are well tolerated, they show a uniform, controllable size distribution, they are easy to manufacture, the polymeric particles have a narrow molecular weight distribution, • they are sufficiently stable to survive passage through the lungs and are therefore also suitable for contrasting the left heart and • they are absorbed by the reticuloendothelial system and are therefore also suitable for contrasting the liver and Spleen.

Insbesondere zeigen die nach den erfindungsgemäßen Verfahren hergestellten Partikeln einen größeren Rückstreukoeffizenten im Vergleich zu den in der EP 0 327 490 offenbarten Partikeln, die ebenfalls aus α-, ß-, γ-Hydroxycarbonsäuren aufgebaut sind. Dieses konnte in einem Vergleichsversuch gezeigt werden. So wurde für eine frisch zubereitete Suspension der in der EP 0 327 490 (Beispiel 1) beschriebenen Partikel in Wasser (Konzentration 18,6 mg/ml) nach 5 Minuten einIn particular, the particles produced by the process according to the invention show a larger backscattering coefficient in comparison to the particles disclosed in EP 0 327 490, which are likewise composed of α-, β-, γ-hydroxycarboxylic acids. This could be shown in a comparative experiment. So for a freshly prepared suspension of the particles described in EP 0 327 490 (Example 1) in water (concentration 18.6 mg / ml) after 5 minutes

Rückstreukoeffizent von αs = 4 x 10* [dB/cm] bei 5 MHz Sendefrequenz gemessen, wohingegen für eine erfindungsgemäße Präparation (Partikel nach Beispiel 1 suspendiert in Wasser/Konzentration 0,18 mg/ml) unter sonst identischen Bedingungen ein Rückstreukoeffizient von αs = 2,7 x 10_1 [dB/cm] gemessen wurde. Berücksichtig man, daß die Konzentration der erfindungsgemäßen Präparation um den Faktor 100 geringer war als die Vergleichspräparation, so ergibt sich ein Anstieg der Rückstreukoeffizienten um fünf Zehnerpotenzen. Da der bildgebende Effekt direkt vom Rückstreukoeffizienten abhängig ist, stellen die erfmdungsgemäß hergestellten Partikel deutlich effektivere Kontrastmittel dar.Backscatter coefficient of α s = 4 x 10 * [dB / cm] measured at 5 MHz transmission frequency, whereas for a preparation according to the invention (particles according to Example 1 suspended in water / concentration 0.18 mg / ml) under otherwise identical conditions a backscatter coefficient of α s = 2.7 x 10 _1 [dB / cm] was measured. If one takes into account that the concentration of the preparation according to the invention was lower by a factor of 100 than the comparative preparation, there is an increase in the backscatter coefficients by five powers of ten. Since the imaging effect is directly dependent on the backscatter coefficient, the particles produced according to the invention represent significantly more effective contrast agents.

Die Bestimmung der Rückstreukoeffizienten erfolgt in einem in vitro Versuchsaufbau, bei dem der von einem in einer Küvette befindlichen Kontrastmittel verursachte rückgestreute Signal gemessen wird (siehe auch "Standardisation of the measurement of acoustical parameters of ultrasound contrast agents" First European Symposium on Ultrasound Contrast Imaging, January 25-26, 1996, Rotterdam).The backscatter coefficients are determined in an in vitro test setup in which the backscattered signal caused by a contrast medium in a cuvette is measured (see also "Standardization of the measurement of acoustical parameters of ultrasound contrast agents" First European Symposium on Ultrasound Contrast Imaging, January 25-26, 1996, Rotterdam).

Die nachfolgenden Beispiele dienen der näheren Erläuterung des Erfindungsgegenstandes, ohne ihn auf diese beschränken zu wollen. The following examples serve to explain the subject matter of the invention in more detail, without wishing to restrict it to them.

Beispiel 1example 1

3 g Polymer Resomer* RG-502 (Böhringer Ingelheim) werden in 40 ml Methylenchlorid/ Aceton (Volumenanteil 50:50) gelöst. 10 ml Perfluoropentan werden mittels Ultraturrax (10.000 Upm) 2 min lang in der Polymerlösung dispergiert. Die entstandene Emulsion (0/0) wird in 400 ml 1 %ige Gelatine Lösung, die auf 0°C temperiert ist, mittels eines mechanischen Rührers (Dispermat-FT, VMA-Getzmann GmbH), (1000 Upm) 30 min lang dispergiert. Die Emulsion (0/0/W) wird in einem 2 1 Dreihalskolben, versehen mit einem Rührer (300 Upm) überführt, 3 h lang bei 20°C durch ^-Einleitung, 3 Stunden lang bei 25 °C durch Vakuum das Lösungsmittel entfernt. Anschließend wird die Suspension mit einem Kryoprotektor vermischt und gefriergetrocknet .3 g of polymer resomer * RG-502 (Böhringer Ingelheim) are dissolved in 40 ml of methylene chloride / acetone (50:50 by volume). 10 ml of perfluoropentane are dispersed in the polymer solution by means of Ultraturrax (10,000 rpm) for 2 minutes. The resulting emulsion (0/0) is dispersed in 400 ml of 1% gelatin solution, which is heated to 0 ° C., using a mechanical stirrer (Dispermat-FT, VMA-Getzmann GmbH), (1000 rpm) for 30 minutes. The emulsion (0/0 / W) is transferred to a 2 1 three-necked flask equipped with a stirrer (300 rpm), the solvent is removed at 20 ° C. for 3 hours by ^ introduction, and at 25 ° C. for 3 hours . The suspension is then mixed with a cryoprotector and freeze-dried.

Das mit Wasser resuspendierte Lyophilisat enthält Mikropartikel (Durchmesser 0,2-8 μm) und zeigt einen hervorragenden in vitro Rückstreukoeffizienten [αs = 2,7 x 10 1 [dB/cm] bei 5 mHz Senderfrequenz und einer Teilchenzahl von C = 4 x 106]. Die Bestimmung der Partikeldurchmesser erfolgte na einem LS-130 der Firma Coulter Electronics GmbH, welche eine Kombination aus Lichtstreuung und Frauenhofer- Beugung ausführt. Die Bestimmung Teilchenanzahl erfolgte mit einem Coulter Counter.The water-resuspended lyophilisate contains microparticles (diameter 0.2-8 μm) and shows an excellent in vitro backscatter coefficient [α s = 2.7 x 10 1 [dB / cm] at 5 mHz transmitter frequency and a particle number of C = 4 x 10 6 ]. The particle diameter was determined using an LS-130 from Coulter Electronics GmbH, which uses a combination of light scattering and Frauenhofer diffraction. The number of particles was determined using a Coulter Counter.

Beispiel 2Example 2

Es wird wie in Beispiel 1 verfahren, wobei Perfluoropentan durch Perfluorodecalin ersetzt wird. Das mit dem Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.The procedure is as in Example 1, with perfluoropentane being replaced by perfluorodecalin. The lyophilisate resuspended with the water contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 3Example 3

Es wird wie in Beispiel 1 verfahren, wobei Perfluoropentan durch Perfluorohexan ersetzt wird. Das mit 0,9%iger NaCl-Lösung resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.The procedure is as in Example 1, with perfluoropentane being replaced by perfluorohexane. The lyophilisate resuspended with 0.9% NaCl solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 4Example 4

Es wird wie in Beispiel 1 verfahren, wobei Perfluoropentan durch Perfluoro- 1.3- Dimethylcyclohexan ersetzt wird.The procedure is as in Example 1, with perfluoropentane being replaced by perfluoro- 1,3-dimethylcyclohexane.

Das mit 5%iger Mannitol-Lösung resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser. Beispiel 5The lyophilisate resuspended with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm. Example 5

Es wird wie in Beispiel 1 verfahren, wobei Perfluoropentan durch Perfluoroheptan ersetzt wird. Das mit 5%iger Mannitol-Lösung resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.The procedure is as in Example 1, with perfluoropentane being replaced by perfluoroheptane. The lyophilisate resuspended with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 6Example 6

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer* RG-502 durch Resomer® RG-503 ersetzt wird. Das mit 0,9%iger NaCl-Lösung resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Procedure is as in Example 1, wherein the polymer Resomer® RG-502 is replaced by Resomer ® RG-503 *. The lyophilisate resuspended with 0.9% NaCl solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 7Example 7

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG-502 durch Resomer® RG-504 ersetzt und in 45 ml Methylchlorid/Aceton (Volumentanteil 55:45) gelöst wird. Das mit 0,9%iger NaCl-Lösung aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Procedure is as in Example 1, wherein the polymer Resomer ® RG-502 is replaced and Resomer ® RG-504 is dissolved in 45 ml of methylene chloride / acetone (volume 55:45). The lyophilisate absorbed with 0.9% NaCl solution contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 8Example 8

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG-502 durch Resomer® RG-756 ersetzt und in 50 ml Methylchlorid/Aceton (Volumentanteil 60:40) gelöst wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Procedure is as in Example 1, wherein the polymer Resomer ® RG-502 is replaced and Resomer ® RG-756 is dissolved in 50 ml of methylene chloride / acetone (volume 60:40). The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 9Example 9

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG-502 durch Resomer® RG-858 ersetzt und in 65 ml Methylchlorid/Aceton (Volumentanteil 63:37) gelöst wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Procedure is as in Example 1, wherein the polymer Resomer ® RG-502 is replaced and Resomer ® RG-858 is dissolved in 65 ml of methylene chloride / acetone (volume 63:37). The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 10 Es wird wie in Beispiel 1 verfahren, wobei Perfluoropentan durch Perfluorohexan und das Polymer Resomer® RG-502 durch Resomer® RG-858 ersetzt und in 65 ml Methylchlorid/Aceton (Volumentanteil 63:37) gelöst wird. Das mit Wasser aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Example 10 procedure is as in Example 1 using perfluoropentane is replaced by perfluorohexane and the polymer Resomer ® RG-502 by Resomer ® RG-858 and dissolved in 65 ml of methylene chloride / acetone (volume 63:37). That with water Lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 11Example 11

Es wird wie in Beispiel 1 verfahren, wobei Perfluoropentan durch Perfluorodecalin und das Polymer Resomer® RG-502 durch Resomer® RG-858 ersetzt und in 65 ml Methylchlorid/Aceton (Volumentanteil 63:37) gelöst wird. Das mit Wasser aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Procedure is as in Example 1 using perfluoropentane is replaced by perfluorodecalin and the polymer Resomer ® RG-502 by Resomer ® RG-858 and dissolved in 65 ml of methylene chloride / acetone (volume 63:37). The water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 12Example 12

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG-502 durch Resomer® R-208 ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.Procedure is as in Example 1, wherein the polymer Resomer ® RG-502 is replaced by Resomer ® R-208th The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 13 Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Ethylacetat ersetzt wird. Das mit Wasser aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0.2 bis 8 μm Durchmesser.Example 13 The procedure is as in Example 1, with acetone being replaced by ethyl acetate. The water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 14Example 14

Es wird wie in Beispiel 1 verfahren, wobei das Aceton durch Methylacetat ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.The procedure is as in Example 1, the acetone being replaced by methyl acetate. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 15Example 15

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG-502 durch Resomer® RG-858 und Aceton durch Ethylacetat ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 - 8 μm Durchmesser. Beispiel 16Procedure is as in Example 1, wherein the polymer Resomer ® RG-502 is replaced by Resomer ® RG-858 and acetone by ethyl acetate. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 - 8 μm. Example 16

Es wird wie in Beispiel 1 verfahren, wobei das Perfluoropentan durch 10 ml 20% ige Glucose-Lösung ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser.The procedure is as in Example 1, the perfluoropentane being replaced by 10 ml of 20% glucose solution. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm.

Beispiel 17Example 17

Es wird wie in Beispiel 1 verfahren, wobei anstelle von 3 g lediglich 2 g Polymer Resomer® RG-502 eingesetzt wird. Das mit 5%iger Mannitol-Lösung aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0, 1 bis 8 μm Durchmesser.The procedure is as in Example 1, using only 2 g of Polymer Resomer ® RG-502 instead of 3 g. The lyophilisate taken up with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.1 to 8 μm.

Beispiel 18Example 18

Es wird wie in Beispiel 1 Verfahren, wobei das Polymer Resomer® RG-502 durch lg PHB/PHN Copolymer (12% PHV, Biopol ICI), Gelatine Lösung durch 200 ml, 1 %Is as in Example 1, wherein the polymer Resomer ® RG-502 by LG PHB / PHN copolymer (12% PHV, Biopol ICI), gelatin solution through 200 ml, 1%

PVA Lösung (MW 9 - 10 x 103 Dalton) ersetzt, das Polymer in 30 mlPVA solution (MW 9 - 10 x 10 3 Dalton) replaced, the polymer in 30 ml

Methylenchlorid/Aceton (Volumenanteil 66 : 34) gelöst wird.Methylene chloride / acetone (66:34 by volume) is dissolved.

Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel vonThe water-resuspended lyophilisate contains ultrasound-active microparticles of

0,4 bis 8 μm Durchmesser.0.4 to 8 μm diameter.

Beispiel 19Example 19

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG 502 durch 1 g PHB/PVB Copolymer (18% PHV, Biopol ICI), Gelatine Lösung durch 200 ml 1 % PVA Lösung in 30 ml Methylenchlorid/ Aceton (Volumenanteil 66 : 34) gelöst wird. Das mit dem Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,4 bis 8 μm Durchmesser.The procedure is as in Example 1, with the polymer Resomer ® RG 502 using 1 g PHB / PVB copolymer (18% PHV, Biopol ICI), gelatin solution using 200 ml 1% PVA solution in 30 ml methylene chloride / acetone (volume fraction 66: 34) is solved. The lyophilisate resuspended with the water contains ultrasound-active microparticles with a diameter of 0.4 to 8 μm.

Beispiel 20Example 20

Es wird wie in Beispiel 1 verfahren, wobei das Polymer Resomer® RG 502 durch 1 g Polycaprolactome [inherent vis: 1.26 dl/g in CHC13 bei 30 °C (Birmingham Polymers NC, USA], Gelatine durch 200 ml 1 % PVA Lösung (MW 9 - 10 kDal) ersetzt, das Polymer in 30 ml Methylenchlorid/ Aceton (Volumentanteil 70 : 30 ) gelöst wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,2 bis 8 μm Durchmesser. Beispiel 21Procedure is as in Example 1, wherein the polymer Resomer ® RG 502 by 1 g Polycaprolactome [inherent vis: 1.26 dl / g in CHC1 3 at 30 ° C (Birmingham Polymers NC, USA], gelatin by 200 ml 1% PVA solution (MW 9-10 kDal), the polymer is dissolved in 30 ml methylene chloride / acetone (70:30 by volume) The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.2 to 8 μm. Example 21

Es wird wie in Beispiel 1 verfahren, wobei Gelatine durch 400 ml, 3% Pluronic® F 68 Lösung ersetzt wird. Das mit 5% Mannitollösung resuspendierte Lyophilisat enthält ultraschallaktiven Mikropartikel von 0,4 bis 8 μm Durchmesser.Procedure is as in Example 1, wherein gelatin is replaced by 400 ml of 3% Pluronic ® F 68 solution. The lyophilisate resuspended with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.4 to 8 μm.

Beispiel 22Example 22

Es wird wie in Beispiel 1 verfahren, wobei Gelatine durch 400 ml, 0.5% Na-Oleat Lösung ersetzt wird. Das mit 5% Mannitollösung aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0,5 bis 8 μm Durchmesser.The procedure is as in Example 1, with gelatin being replaced by 400 ml of 0.5% Na oleate solution. The lyophilisate absorbed with 5% mannitol solution contains ultrasound-active microparticles with a diameter of 0.5 to 8 μm.

Beispiel 23 Es wird wie in Beispiel 1 verfahren, wobei Gelatine durch 400 ml, 1 % Octyl-ß-D- Glucopyranosid Lösung ersetzt wird.Example 23 The procedure is as in Example 1, with gelatin being replaced by 400 ml, 1% octyl-β-D-glucopyranoside solution.

Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0, 1 bis 8 μm Durchmesser.The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 8 μm.

Beispiel 24Example 24

Es wird wie in Beispiel 1 verfahren, wobei Gelatine Lösung durch 400 ml, 1 % Saccharosepaimitat P-1570 (Ryoto Sugarester) versetzt wird.The procedure is as in Example 1, with the gelatin solution being mixed with 400 ml, 1% sucrose pitate P-1570 (Ryoto Sugarester).

Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0, 1 bis 7 μm Durchmesser.The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 μm.

Beispiel 25Example 25

Es wird wie in Beispiel 1 verfahren, wobei Gelatine Lösung durch 400 ml, 1 % Saccharose Stearat (Ryoto Sugarester) S-1670 versetzt wird.The procedure is as in Example 1, with gelatin solution being mixed with 400 ml, 1% sucrose stearate (Ryoto Sugarester) S-1670.

Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0,1 bis 7 μm Durchmesser. Beispiel 26The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 μm. Example 26

Es wird wie in Beispiel 1 verfahren, wobei anstelle von Gelatine Lösung, 400 ml, 1 % Saccharosediester, SP 70 (Sisternen, The Netherlands) eingesetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0, 1 bis 7 μm Durchmesser.The procedure is as in Example 1, with 400 ml, 1% sucrose diester, SP 70 (Sisternen, The Netherlands) being used instead of gelatin solution. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 μm.

Beispiel 27Example 27

Es wird wie in Beispiel 1 verfahren, wobei Methylenchlorid/ Aceton Lösungsgemisch durch 70 ml Ethylacetat ersetzt, anstelle von 10 ml Perfluoropentan 18 ml Perfluropentan eingesetzt wird.The procedure is as in Example 1, methylene chloride / acetone solution mixture being replaced by 70 ml of ethyl acetate, 18 ml of perfluoropentane being used instead of 10 ml of perfluoropentane.

Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 0, 1 bis 5 μm Durchmesser.The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 5 μm.

Beispiel 28Example 28

Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Ethylacetat ersetzt wird. Das mit Wasser aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0,1 bis 7 μm Durchmesser.The procedure is as in Example 1, with acetone being replaced by ethyl acetate. The water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 7 μm.

Beispiel 29Example 29

Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Methylacetat ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 1 bis 7 μm Durchmesser.The procedure is as in Example 1, with acetone being replaced by methyl acetate. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 7 μm.

Beispiel 30Example 30

Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Methylactat ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 1 bis 6 μm Durchmesser.The procedure is as in Example 1, with acetone being replaced by methyl lactate. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 6 μm.

Beispiel 31 Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Ethylactat ersetzt wird.EXAMPLE 31 The procedure is as in Example 1, acetone being replaced by ethyl acetate.

Das mit Wasser aufgenommene Lyophilisat enthält ultraschallaktive Mikropartikel von 0,1 bis 6 μm Durchmesser. Beispiel 32The water-absorbed lyophilisate contains ultrasound-active microparticles with a diameter of 0.1 to 6 μm. Example 32

Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Triacetin ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 1 bis 7 μm Durchmesser.The procedure is as in Example 1, with acetone being replaced by triacetin. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 7 μm.

Beispiel 33Example 33

Es wird wie in Beispiel 1 verfahren, wobei Aceton durch Triethylcitrat ersetzt wird. Das mit Wasser resuspendierte Lyophilisat enthält ultraschallaktive Mikropartikel von 1 bis 7 μm Durchmesser.The procedure is as in Example 1, with acetone being replaced by triethyl citrate. The water-resuspended lyophilisate contains ultrasound-active microparticles with a diameter of 1 to 7 μm.

Beispiel 34 0,375 g L-Lysin (Aldrich) werden in 25 ml Eisessig (Merck) gelöst; 2,5 g Resomer® RG-756 (Böhringer Ingelheim) werden in 75 ml Dichlormethan (Merck) gelöst. Die vereinigten Lösungen in einer Apparatur wie in Figur 1 abbgebildet weiter behandelt.Example 34 0.375 g of L-lysine (Aldrich) are dissolved in 25 ml of glacial acetic acid (Merck); 2.5 g Resomer ® RG-756 (Böhringer Ingelheim) are dissolved in 75 ml dichloromethane (Merck). The combined solutions were further treated in an apparatus as shown in FIG. 1.

Dazu werden die vereinigten Lösungen zunächst in ein Reservoir (17) gegeben und die Anlage über Ventil (2) und Leitung (30) aus einer Vorratsflaschen mit dem Gas befüllt. Mittels einer Kolbenhubpumpe (16) wird die Lösung aus dem Reservoir (17) nach Durchströmen von Leitung (52), einem Wärmetauscher (15), einer Leitung (54). einem Ventil (20) und schließlich Leitung (55), der Düse (118) zugeleitet. Mit einem Druck von 94-96 bar wird die Copolymer enthaltende Lösung durch eine konventionelle Einstoffdüse (118) [Typ Schlick 121 V] in die Kolonne (12) versprüht, wobei gleichzeitig CO2 im überkritischen Zustand mit 90 bar/36 ° C und einem Durchsatz von 8,9 kg/h im Gleichstrom, über Einlaß (8), durch die Kolonne geleitet wird. Die Düse hat einen Durchmesser von 0,5 mm, der Sprühwinkel beträgt 10°.For this purpose, the combined solutions are first placed in a reservoir (17) and the system is filled with the gas from a supply bottle via valve (2) and line (30). The solution is removed from the reservoir (17) by means of a piston stroke pump (16) after flowing through line (52), a heat exchanger (15), a line (54). a valve (20) and finally line (55) to the nozzle (118). At a pressure of 94-96 bar, the copolymer-containing solution is sprayed into the column (12) through a conventional single-substance nozzle (118) [Schlick 121 V], while at the same time CO2 in the supercritical state at 90 bar / 36 ° C and a throughput of 8.9 kg / h in cocurrent, is passed through the column via inlet (8). The nozzle has a diameter of 0.5 mm, the spray angle is 10 °.

Entsprechend der hohen Affinität des überkritischen CO2 zum Lösungsmittel wird den primär gebildeten Tröpfchen Lösungsmittel entzogen. Zurück bleiben kugelförmige feste Polymerpartikeln.In accordance with the high affinity of the supercritical CO 2 for the solvent, the primarily formed droplets of solvent are extracted. This leaves spherical solid polymer particles.

Die weiteren Schritte dienen im wesentlichen der Reinigung und Rückführung des Lösungsmittelbeladenen CO2, haben aber mit der Herstellung der Partikel nichts mehr zu tun. Die Aufbereitung des CO2 kann wie folgt geschehen. Das mit dem Lösemittel beladene Gas entströmt durch Leitungen (42) und (40), gesteuert durch 2 Magnetventile (7 und 9), dem Kolonnenende und wird auf 60 bar entspannt. Die Ventile sind so geschaltet, daß die pro Zeiteinheit in die Kolonne einströmende Menge des fluiden Gases unter Aufrechthaltung des Arbeitsdruckes der Kolonne entströmen kann. Das durch die Entspannung auf 60 bar abgekühlte, mit Lösungsmittel beladene CO2 wird mittels Leitung (62) in den auf 21 ° C temperierten Separator (10) geleitet, wo sich das Lösungsmittelgemisch infolge der unter diesen Bedingungen stark verminderten Löslichkeiten im CO abscheidet. Das vom Lösungsmittelgemisch befreite CO2 wird mittels Leitung (64 und 32) durch Druck- und Temperaturerhöhung (3 und 4) erneut in den überkritischen Zustand überführt (90 bar, 36° C) und zur weiteren Trocknung der entstandenen Partikel erneut der Kolonne über Leitung (34), Flüssiggaspumpe (4), Leitung (36), Wärmetauscher (5), Leitung (38) durch Einlaß (8) zugeführt.The further steps essentially serve to clean and recycle the solvent-laden CO 2 , but have nothing to do with the production of the particles. The CO 2 can be processed as follows. The gas loaded with the solvent flows through lines (42) and (40), controlled by 2 solenoid valves (7 and 9), to the end of the column and is expanded to 60 bar. The Valves are switched so that the amount of fluid gas flowing into the column per unit of time can escape while maintaining the working pressure of the column. The CO 2 , which has been cooled to 60 bar by the expansion and is loaded with solvent, is fed via line (62) into the separator (10), which is heated to 21 ° C., where the solvent mixture separates out in the CO as a result of the greatly reduced solubilities under these conditions. The CO 2 freed from the solvent mixture is transferred again to the supercritical state by means of line (64 and 32) by increasing the pressure and temperature (3 and 4) (90 bar, 36 ° C.) and again to the column via line to further dry the resulting particles (34), LPG pump (4), line (36), heat exchanger (5), line (38) through inlet (8).

Die Entnahme des im Separator (10) abgetrennten Lösungsmitte lgemischs erfolgt nach Abtrennung des Separators (10) aus dem Kreislauf durch Ventile (6) und (13) und Entspannung auf Atmosphärendruck über das Ventil (72).The solvent mixture separated in the separator (10) is removed after separating the separator (10) from the circuit by means of valves (6) and (13) and relaxing to atmospheric pressure via the valve (72).

Nachdem die gesamte im Reservoir enthaltene Menge an gelöstem Polymer versprüht wurde (Zeitdauer je nach Druck 20 bis 50 min), wird noch solange CO2 durch die Kolonne geleitet, bis im Separator (10) keine Lösungsmittelreste mehr zurückgewonnen werden können.After the entire amount of dissolved polymer contained in the reservoir has been sprayed (time depending on pressure 20 to 50 min), CO 2 is passed through the column until no solvent residues can be recovered in the separator (10).

Nach Abschluß des Trocknungsvorganges wird der CO2-Strom zur Kolonne abgestellt, die Kolonne über die Ventile (11) und (14) auf Atmosphärendruck entspannt und die Partikel am unteren Kolonnenende (19) entnommen.After the drying process has ended, the CO 2 stream to the column is shut off, the column is expanded to atmospheric pressure via valves (11) and (14) and the particles are removed at the lower end of the column (19).

Es werden ultraschallaktive, gashaltige Mikropartikel mit einem Durchmesser von 5-10 μm erhalten.Ultrasound-active, gas-containing microparticles with a diameter of 5-10 μm are obtained.

Beispiel 35Example 35

0,375 g L-Lysin (Aldrich), 2,5 g Polymer (RG-756) werden in 25 ml Eisessig (Merck) und 75 ml Dichlormethan (Merck) gelöst und solange gerührt, bis eine klare Lösung entstanden ist. Die weitere Umsetzung erfolgt analog zu Beispiel 34.0.375 g L-lysine (Aldrich), 2.5 g polymer (RG-756) are dissolved in 25 ml glacial acetic acid (Merck) and 75 ml dichloromethane (Merck) and stirred until a clear solution is obtained. The further implementation is carried out analogously to Example 34.

Es werden ultraschallaktive, gashaltige Mikropartikel mit einem Durchmesser von 5-10 μm erhalten. Beispiel 36-41Ultrasound-active, gas-containing microparticles with a diameter of 5-10 μm are obtained. Example 36-41

Die Herstellung weitere Mikropartikel erfolg analog zu Beispiel 34. Die jeweils verwendeten Polymeren sowie weitere Daten sind in Tabelle 1 zusammengefaßt.Further microparticles are produced analogously to Example 34. The polymers used in each case and further data are summarized in Table 1.

In allen Fällen werden ultraschallaktive, gashaltige Mikropartikel erhalten.In all cases, ultrasound-active, gas-containing microparticles are obtained.

Die erhaltenen ultraschallaktiven, hohlen Mikropartikeln sind steril und frei von Lösemittelrückständen, Polymerisationskatalysatoren oder Initiatormolekülen. Sie besitzen eine gleichmäßige Teilchengrößenverteilung von 5 bis 10 μm.The ultrasound-active, hollow microparticles obtained are sterile and free from solvent residues, polymerization catalysts or initiator molecules. They have a uniform particle size distribution of 5 to 10 μm.

Die Polymere werden jeweils in 75 ml Dichlormethan (Merck) und 25 ml Eisessig gelöst, die jeweilige Menge Aminosäure wird zugegeben. D,L-Phenylalanin ist geeigneterweise in bis 50 ml Ethanol (Merck) vorzulösen.The polymers are each dissolved in 75 ml dichloromethane (Merck) and 25 ml glacial acetic acid, the respective amount of amino acid is added. D, L-phenylalanine is suitably pre-dissolved in up to 50 ml of ethanol (Merck).

Versuchs- Polymer bzw. Einwaage Aminosäure Einwaage Molverhältnis πummer Copolymer Polymer [g] Aminosäure [g] Lactid/GlycolidExperimental polymer or weighed-in amino acid weighed-in molar ratio number copolymer polymer [g] amino acid [g] lactide / glycolide

36 Poly-(D,L)-lacti_ 2,0 L-Lysin 0,536 poly (D, L) lacti 2.0 L-lysine 0.5

37 Poly-(D,L)-lactid- 1.0 L-Phenyl-alanin 0,25 75 : 25 coglycolid37 poly (D, L) lactide-1.0 L-phenylalanine 0.25 75:25 coglycolide

38 Poly-(D,L)-lactid- 2,0 D,L-Phenyl-alanin 0,5 75 : 25 coglycolid38 poly (D, L) lactide 2.0 D, L-phenylalanine 0.5 75:25 coglycolide

39 Poly-(D,L)-lactid- 2,2 L-Tryptophan 0,55 75 : 25 coglycolid39 poly- (D, L) -lactide-2.2 L-tryptophan 0.55 75:25 coglycolide

40 Poly-L-lactid 6,0 L-Lysin 0,940 poly-L-lactide 6.0 L-lysine 0.9

41 Poly-L-lactid 3,0 L-Lysin 0,4541 poly-L-lactide 3.0 L-lysine 0.45

Tabelle 1 Table 1

Claims

Patentansprüche claims 1. Verfahren zur Herstellung von gasenthaltenden Mikropartikeln für die Ultraschalldiagnostik, deren Wandmaterial aus Polyestem von α-, ß- oder γ- Hydroxycarbonsäuren aufgebaut ist, dadurch gekennzeichnet, daß1. A process for the preparation of gas-containing microparticles for ultrasound diagnostics, the wall material of which is composed of polyesters of α-, β- or γ-hydroxycarboxylic acids, characterized in that (i) der jeweilige Polyester und gegebenenfalls eine oberflächenaktive Substanz in einem organischen Lösungsmitteln oder Lösungsmittelgemischen, von denen mindestens ein Lösungsmittel mit Wasser gut mischbar ist, gelöst wird, anschließend eine perfluorierte Verbindung oder Wasser in dieser Lösung dispergiert wird und anschließend diese Dispersion in Wasser, das eine oberflächenaktive Substanz enthält, mittels eines Rührers dispergiert wird, wobei das Lösungsmittel durch Gaseinleitung und Anlegen eines Vakuums entfernt wird und abschließend die so erhaltene Suspension mit einem geeigneten pharmazeutisch akzeptablen Kryoprotektor vermischt und gefriergetrocknet wird oder daß(i) the respective polyester and optionally a surface-active substance are dissolved in an organic solvent or solvent mixture, of which at least one solvent is readily miscible with water, then a perfluorinated compound or water is dispersed in this solution and then this dispersion in water, which contains a surface-active substance, is dispersed by means of a stirrer, the solvent being removed by introducing gas and applying a vacuum, and finally the suspension thus obtained is mixed with a suitable pharmaceutically acceptable cryoprotector and freeze-dried or that (ii) das (die) gewünschte(n) Polyester und gegebenenfalls eine Aminosäure in mindestens einem organischen Lösungsmittel gelöst wird (werden), diese Lösung über eine Düse in eine Kolonne gespüht wird, die mit einem überkritischen Gas befüllt ist oder von diesem durchströmt wird, wobei das(ii) the desired polyester (s) and optionally an amino acid is (are) dissolved in at least one organic solvent, this solution is sprayed through a nozzle into a column which is filled with or through which a supercritical gas flows , the Lösungsmittel vom überkritischen Gas aufgenommen wird.Solvent is absorbed by the supercritical gas. 2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß das Wandmaterial aus Polyglycolid (PGA) sowie dessen Copolymere mit L-Lactid (PGA/PLLA) oder PolyLactid (PLA) sowie dessen Stereocopolymere wie z.B. Poly-L-Lactid2. The method according to claim 1, characterized in that the wall material made of polyglycolide (PGA) and its copolymers with L-lactide (PGA / PLLA) or polyLactide (PLA) and its stereocopolymers such as e.g. Poly-L-lactide (PLLA), Poly-DL-Lactid oder L-Lactid/DL-Lactid oder Poly-ß-hydroxybutyrat (PHBA) sowie dessen Copolymere mit ß-Hydroxyvalerat (PHBA/HVA) oder Poly-ß-hydroxypropionat (PHPA) oder Poly-p-dioxanon (PDS) oder Poly-δ- valerolacton oder Poly-ε-caprolacton besteht.(PLLA), poly-DL-lactide or L-lactide / DL-lactide or poly-ß-hydroxybutyrate (PHBA) as well as its copolymers with ß-hydroxyvalerate (PHBA / HVA) or poly-ß-hydroxypropionate (PHPA) or poly- p-dioxanone (PDS) or poly-δ-valerolactone or poly-ε-caprolactone. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß bei Copolymeren aus Milchsäure und Glycolsäure das Mischungsverhältnis im Bereich von 85:15 bis 50:50 liegt.3. The method according to claim 1 or 2, characterized in that in the case of copolymers of lactic acid and glycolic acid, the mixing ratio is in the range from 85:15 to 50:50. 4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß als Lösungsmittel Dichlormethan, Aceton, Ethylacetat, Methylacetat, Triacetin, Triethylcitrat, Ethyllactat. Isopropylacetat, Propylformiat, Butylformiat, Ethylformiat und/oder Methyllactat verwendet werden. 4. Verfahren nach Anspruch 1 (i), dadurch gekennzeichnet, daß als perfluorierte Verbindungen Perfluoropentan, Perfluorohexan, Perfluoro- 1,3- Dimethylcyclohexan, Perfluorocyclohexen, Perfluorodecalin und/oder Perfluoroether verwendet wird.4. The method according to claim 1, characterized in that the solvent is dichloromethane, acetone, ethyl acetate, methyl acetate, triacetin, triethyl citrate, ethyl lactate. Isopropyl acetate, propyl formate, butyl formate, ethyl formate and / or methyl lactate can be used. 4. The method according to claim 1 (i), characterized in that perfluorinated compounds perfluoropentane, perfluorohexane, perfluoro-1,3-dimethylcyclohexane, perfluorocyclohexene, perfluorodecalin and / or perfluoroether is used as perfluorinated compounds. 5. Verfahren nach Anspruch 1 (i), dadurch gekennzeichnet, daß als oberflächenaktive Substanz Substanzen aus der Gruppe der Poloxamere oder Poloxamine, Polyethylenglycol Alkylether, Polysorbate, Saccharoseester, Saccharoseester, Gelatine, Polyvinylpyrolidon, Fettalkoholpolyglycosid,5. The method according to claim 1 (i), characterized in that as a surface-active substance substances from the group of poloxamers or poloxamines, polyethylene glycol alkyl ethers, polysorbates, sucrose esters, sucrose esters, gelatin, polyvinyl pyrolidone, fatty alcohol polyglycoside, Chaps, Chap, Chapso, Decyl-ß-D-glycopyranosid, Decyl-ß-D-maltopyranosid, Dodecyl-ß-D-maltopyranosid, Natriumoleat, Polyethylenglykol, Polyvinylalkohol oder deren Gemische verwendet werden.Chaps, Chap, Chapso, decyl-β-D-glycopyranoside, decyl-β-D-maltopyranoside, dodecyl-β-D-maltopyranoside, sodium oleate, polyethylene glycol, polyvinyl alcohol or mixtures thereof. 6. Verfahren nach Anspruch 1 (ii), dadurch gekennzeichnet, daß als Aminosäure L-Lysin, L-Phenylalanin, L-Tryptophan und/oder D,L-Phenylalanin verwendet wird.6. The method according to claim 1 (ii), characterized in that L-lysine, L-phenylalanine, L-tryptophan and / or D, L-phenylalanine is used as the amino acid. 7. Verfahren nach Anspruch 1 (ii), dadurch gekennzeichnet, daß als überkritisches Gas Distickstoffoxid, Kohlendioxid, Halogenkohlenwasserstoffe, gesättigte oder ungesättigte gasförmige Kohlenwasserstoffe, Stickstoffdioxid und/oder Ammoniak verwendet wird.7. The method according to claim 1 (ii), characterized in that nitrous oxide, carbon dioxide, halogenated hydrocarbons, saturated or unsaturated gaseous hydrocarbons, nitrogen dioxide and / or ammonia is used as the supercritical gas. 8. Verfahren nach Anspruch 1 (ii) dadurch gekennzeichnet, daß die Lösung mit einem Oberdruck von 94-96 bar durch eine konventionelle Einstoffdüse mit einem Düsendurchmesser von 0,5 mm und einem Sprühwinkel von 10° versprüht wird.8. The method according to claim 1 (ii), characterized in that the solution is sprayed with an upper pressure of 94-96 bar through a conventional single-substance nozzle with a nozzle diameter of 0.5 mm and a spray angle of 10 °. 9. Mikropartikel für die Ultraschalldiagnostik hergestellt nach dem in Anspruch 1 genannten Verfahren.9. Microparticles for ultrasound diagnostics produced by the method mentioned in claim 1. 10. Mikropartikel für die Ultraschalldiagnostik hergestellt nach den in Anspruch 1 genannten Verfahren enthaltend als Gas Luft, Stickstoff, Sauerstoff, Edelgase, Distickstoffoxid, Kohlendioxid, Halogenkohlenwasserstoffe, gesättigte oder ungesättigte gasförmige Kohlenwasserstoffe, Stickstoffdioxid und/oder10. Microparticles for ultrasound diagnostics produced by the methods mentioned in claim 1, containing gas, air, nitrogen, oxygen, noble gases, nitrous oxide, carbon dioxide, halogenated hydrocarbons, saturated or unsaturated gaseous hydrocarbons, nitrogen dioxide and / or Ammoniak. Ammonia.
PCT/EP1996/001107 1995-03-14 1996-03-14 Process for producing polymer microparticles, microparticles produced using said process, and the use of such particles in medical diagnostics WO1996028191A1 (en)

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AT96908039T ATE241388T1 (en) 1995-03-14 1996-03-14 METHOD FOR PRODUCING POLYMERIC MICROPARTICLES, MICROPARTICLES PRODUCED BY THIS METHOD AND THEIR USE IN MEDICAL DIAGNOSTICS
US08/913,312 US6468506B1 (en) 1995-03-14 1996-03-14 Process for producing polymeric microparticles, microparticles produced by said process and the use of such particles in medical diagnostics
DE59610478T DE59610478D1 (en) 1995-03-14 1996-03-14 METHOD FOR PRODUCING POLYMERIC MICROPARTICLES, MICROPARTICLES PRODUCED BY THIS METHOD AND THEIR USE IN MEDICAL DIAGNOSTICS
EP96908039A EP0822836B1 (en) 1995-03-14 1996-03-14 Process for producing polymer microparticles, microparticles produced using said process, and the use of such particles in medical diagnostics
JP52728696A JP3943130B2 (en) 1995-03-14 1996-03-14 Method for producing polymer microparticles, microparticles produced by the method and their use in medical diagnostics
CA002214778A CA2214778C (en) 1995-03-14 1996-03-14 Process for the production of polymeric microparticles, microparticles that are produced according to this process as well as their use in medical diagnosis

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DE19510690A DE19510690A1 (en) 1995-03-14 1995-03-14 Polymeric nano- and / or microparticles, processes for their production, and use in medical diagnostics and therapy
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JPH11501647A (en) 1999-02-09
WO1996028192A1 (en) 1996-09-19
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ATE229818T1 (en) 2003-01-15
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ATE241388T1 (en) 2003-06-15
CA2214778A1 (en) 1996-09-19
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US6207135B1 (en) 2001-03-27
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